Britain needs a third high-speed railway line to create "a northern powerhouse", George Osborne said today.

The Chancellor used a speech in Manchester to argue that he wants to go beyond the north-south HS2 to create an east-west HS3.

In doing so he hopes to create "a collection of cities - sufficiently close to each other that combined they can take on the world".

The east-west connection between Leeds and Manchester would be based on existing rail routes but speeded up with new tunnels and infrastructure.

Image Caption:The first phase of HS2

It is an effort to address Britain's financial dependence on London, which currently accounts for nearly a quarter of the country's economic output.

Mr Osborne said: "The cities of the North are individually strong, but collectively not strong enough. The whole is less than the sum of its parts. So the powerhouse of London dominates more and more. And that's not healthy for our economy. It's not good for our country.

Video:MP On HS3 Prospect

"We need a northern powerhouse too. Not one city, but a collection of northern cities - sufficiently close to each other that combined they can take on the world. Able to provide jobs and opportunities and security to the many, many people who live here, and for whom this is all about."

Together, the North's largest cities have a higher population than hubs such as New York and Tokyo, Mr Osborne added.

Under current plans the £50bn HS2 project will provide 225mph trains from London to Birmingham in its first stage, before creating a Y-shaped network with lines to Manchester and Leeds by 2032/33.

Video:Church Opposition To HS2 Route

The £21bn second phase would then connect Leeds and Manchester - but it remains an aspiration rather than a pledge.

The Government claims at least 60,000 jobs would be created in "the most important investment in the north for a century".

The proposal will be seen as an attempt to win support for the Conservatives outside their southern heartlands before the 2015 General Election, but a number of MPs with constituencies along the route are opposed to the project.

Video:Stop HS2 On Campaign Against System

Mr Osborne said: "Of course, there are opponents of the project - just as there were opponents of the original railways. I've discovered that almost everything worth doing in politics is controversial."